The Weak Magneto-Optical Effect Of Nematic Liquid Crystal

Liquid crystal (LC) is like odd axis crystal in optics. It has birefringence, Bragg reflection, diffraction and optical rotation like crystal. LC is easily affected by electric field, magnetic field, temperature, stress and impurity absorption etc., and its optical character begins to change.For the convenient discussion of the optical properties of cholesteric liquid crystal, a new matrix is offered in this paper, which's matrix element is the complex exponential. Using this method we obtain an important conclusion, which is, for the polarized light of wavelength being equal to pitch of the cholesteric liquid crystal, that the linear polarized light is changed into the circular polarized light. The magnetic-effect on polarization plane of light in the twisted nematic liquid crystal is investigated using the dielectric tensor. It is found that the linear-polarized light can be splinted into the left–hand and right-hand elliptically polarized light when it pass through the liquid crystal applied with small magnetic field. The resultant vector has an angle change from the incident light. At the end of this paper, an experiment is shown to prove the rotation angle is related to the wavelength of the incident light.